基于用户视角的组合Web服务响应时间优化

针对响应时间,通过选择、调用合适的成员Web服务,对组合Web服务的QoS进行优化．该优化方法基于用户的视角,将组合Web服务运行时用户一次等待周期中需要执行的所有任务作为一个整体进行调度;同时根据组合Web服务流程的不同环节中用户对等待时间的不同敏感度,设置调度参数,降低关键环节超时的风险．实验表明,此方法可以有效地优化组合Web服务的响应时间,提高用户的满意度和QoS．     

基于成本效益系数的Web服务组合可靠性优化方法

为了解决Web服务组合优化过程计算量大、非线性等问题,提出在给定成本约束下利用成本效益系数(CBC)对Web服务组合可靠性进行优化的方法。首先分析了Web服务组合结构模式及其对应的可靠性函数,进一步给出服务组合的可靠性计算方法,并建立非线性可靠性优化模型;然后,通过组件服务的成本及其可靠性关系计算成本效益系数,进一步确定Web服务组合的优化方案,再根据优化模型计算得到优化结果;最后,以组件服务可靠性数据为基础,通过与传统的优化方法比较,验证了基于成本效益系数的方法可以在给定成本约束时获得更高的可靠性。实验结果表明,所提方法对Web服务组合进行可靠性优化是有效、合理的。     

一种基于扩展Owl-S本体的Web服务质量度量及评价方法的研究

随着Web服务技术的广泛使用,从多个功能相似的Web服务中选取较合适的Web服务成了亟需解决的问题。对Web服务本体Owl-S进行扩展,给Web服务添加加费用、时间、可靠性等服务质量指标。从多个方面获取并规范度量指标,根据这些服务质量指标建立评价模型,根据评价模型得到功能相似Web服务的综合服务质量排序,为服务选取提供依据。     

基于本体分类的Web服务合成的研究及应用

阐述了一个基于本体分类的Web服务合成模型，扩展标准的WSDL服务描述，将Web服务及其参数严格映射到本体概念分类层次，使服务描述保存了语义信息，领域本体过滤确保了合成服务的有效性，基于用户的需求描述实现了从现有Web服务中动态发现、匹配和组合服务的功能的算法，根据用户的服务质量要求，模型还能从生成的合成服务链中筛选出最佳服务组合。整个模型在一定程度上实现了服务合成的自动化。     

面向客户视角的Web服务组合优化与集成管理方法*

现有Web服务组合研究未考虑客户视角的服务质量感知和对功能与质量的均衡需求,无法优化配置网上丰富的Web服务资源并与网下服务资源协同。借鉴已有研究成果,研究基于客户视角的服务组合优化与集成管理问题：建立客户视角的Web服务模型、提出服务组合质量均衡推荐方法、建立服务功能和质量的网上网下集成管理模型。研究有助于提高现代Web服务管理服务水平。     

Web Service Configuration Under Multiple Quality-of-Service Attributes

With the popularity of Internet technology, Web services are becoming the most promising paradigm for distributed computing. However, when a single Web service fails to meet service requestor's multiple function needs, web services need to be dynamically configured together to form a web service composition. Since there may be many configurations providing identical functionality with different quality-of-service (QoS), a choice needs to be made according to users' functional and nonfunctional requirements. In this paper, we formulate a Web service functional configuration problem by using Petri nets. The graph structure and algebraic properties of the model are analyzed in detail to show that a basis solution of a state-shift equation of the Petri net model corresponds to a realizable configuration process. This result is later used to formulate the multiple attribute QoS optimization problem to a linear programming problem. Finally, a case study is performed to show that the proposed analysis result can be effectively applied in practice.     

基于云仿真的Web服务选择研究

针对当前Web服务海量增加,而现有的Web服务选择算法低效、缓慢的问题,提出了一种基于云计算的粒子群优化算法的Web服务选择方法。该方法在云平台下对粒子分群映射、相似分群并行化简、适时更新分群,并且寻找与用户需求最相似、服务质量最好的策略。实验表明,该方法能有效减少流程执行过程中Web服务选择导致的时间开销,并提高Web服务选择的可靠性。     

服务Agent的设计与实现

将Web服务与Agent相结合代表了Web技术的发展方向之一。服务Agent能够管理一组密切相关的Web服务,并智能化地向外界提供综合的、集成的服务功能。服务Agent的能力建立在内部定义的一组规划基础上。在BDIAgent的基础上,本文提出了一种服务Agent的结构定义;提出了基于目标规划的语义模型和基于ECA规则规划的语法模型,用以进行基于事件驱动的规划选择和执行;实现了支持服务Agent建模的可视化工具;最后介绍一个应用实例。     

A decision-making method for personalized composite service

Web services are emerging technologies that enable application to application communication and reuse of autonomous services. Web services composition is a concept of integrating component services to conduct complex business transactions based on functionality and performance constraints. With the rapid growth of Web services on the Internet, the services owing the same functionality and different performance become more and more, and different users care for different quality. Therefore, designing effective decision-making method for the personalized composite service has become a fundamental problem for the application based on Web service. In this paper, oriented to the user need with single optimization objective, an efficient algorithm, which consists of Particle Swarm Optimization (PSO) and Niche technology, is presented to solve the Web service selection problem. Furthermore, in view of the practical composition requirements including multiple optimization objectives, an algorithm used to resolve the service selection with multi-objective multi-constraint is designed based on NPSO and the intelligent optimization theory of multi-objective PSO, which can produce a set of Pareto optimal composite services by means of optimizing various objective functions simultaneously. Experimental results show that NPSO algorithm owns better global convergence ability with faster convergence speed. Meanwhile, multi-objective multi-constraint NPSO is both feasible and efficient.     

一种服务聚合中QoS全局最优服务动态选择算法

Web服务作为一种新型的Web应用模式,近年来得到了迅速的发展.如何动态地把现存的各种Web服务整合起来以形成新的、满足不同用户需求的、增值的复杂服务已成为新的应用需求和研究热点.针对现有服务聚合中服务选择技术的不足,提出了一种解决服务聚合中服务动态选择QoS全局最优化问题的实现算法GODSS(global optimal of dynamic Web services selection).算法的主要思想是把服务动态选择全局最优化问题转化为一个带QoS约束的多目标服务组合优化问题,利用多目标遗传算法的智     

基于领域本体的Web服务动态组合

随着Web环境下服务数量的快速增长,如何自动地根据服务请求,进行服务的动态组合成为一个迫切需要解决的问题,该文提出了一种基于领域本体的服务动态组合方法,该方法利用领域本体及其推理能力,生成一个优化的服务组合图,然后基于该图给出了一个高效的服务组合算法．与已有的方法相比,该文的方法综合考虑了服务语义、服务组合的质量和服务组合的效率等因素,可以自动地根据服务请求实现服务的动态组合．同时保证了服务组合的效率和质量．     

一种基于抽象与精化技术的Web服务组合验证方法

模型检测因其自动化程度高、能够提供反例路径等优势,被广泛应用于Web服务组合的兼容性验证。本文针对模型检测过程中存在的状态爆炸问题,在传统的模型检测方法中引入谓词抽象和精化技术,提出了一种针对Web服务组合的抽象精化验证框架。使用谓词抽象技术对原子Web服务抽象建模,将各Web服务抽象模型组合成组合抽象模型;将模型检测后得到的反例在各原子Web服务上做投影操作,对投影反例进行确认;对产生伪反例的Web服务抽象模型进行精化,生成新的组合抽象模型,再次对性质进行验证。最后通过实例分析说明基于抽象精化技术的Web服务组合验证框架在缓解状态爆炸问题上的可行性。     

基于遗传算法的Web服务组合优化

近年来国内外学术界和行业界围绕着Web服务组合开展了大量的研究工作,这些研究都把重点放在Web服务组合功能的实施上,而对组合服务质量的研究甚少.在建立Web服务组合优化模型的基础上,将遗传算法引入到Web服务组合中去,提出了基于遗传算法的Web服务组合的优化方法,给出了构建基于遗传算法的Web服务组合模型和求解方法,从而可以提高组合服务的质量,并能够使Web服务组合满足个性化需求.     

具有QoS约束的语义Web服务发现的研究

传统的Web服务主要是基于UDDI的技术规范,只提供了按照简单分类和关键字的服务发现方法,造成查准率与查全率低,影响服务复用和服务组合的相容性.带有语义的Web服务通常也只关注服务功能性的匹配,因缺乏服务质量描述和灵活、有效的服务匹配方法,而难以保证服务的全面匹配和快速定位.本文分析了现有的一些相关研究,在Web服务模型的基础上,结合"逐渐逼近"的思想,提出一个三层次的匹配筛选算法,并对基本描述、IOPE、服务质量各层的匹配算法进行了深入讨论,用相似函数来度量服务提供方与服务请求方的Web服务相似程度,为Web服务发现提供了一种有效的方法.     

Composition of Semantic Web services using Linear Logic theorem proving

This paper introduces a method for automatic composition of Semantic Web services using Linear Logic (LL) theorem proving. The method uses a Semantic Web service language (DAML-S) for external presentation of Web services, while, internally, the services are presented by extralogical axioms and proofs in LL. LL, as a resource conscious logic, enables us to capture the concurrent features of Web services formally (including parameters, states and non-functional attributes). We use a process calculus to present the process model of the composite service. The process calculus is attached to the LL inference rules in the style of type theory. Thus, the process model for a composite service can be generated directly from the complete proof. We introduce a set of subtyping rules that defines a valid dataflow for composite services. The subtyping rules that are used for semantic reasoning are presented with LL inference figures. We propose a system architecture where the DAML-S Translator, LL Theorem Prover and Semantic Reasoner can operate together. This architecture has been implemented in Java.     

基于QoS多目标优化的Web服务组合方法

为了确保在服务组合中获得Pareto最优解集,把服务组合建模为多个服务质量属性同时优化的多目标优化问题,提出了一种依据服务质量属性类型的通用预处理方法,采用多个信息素表和单个启发式信息表的多目标蚁群算法,蚂蚁随机选择一种信息素表建构可行解,每个蚁群周期完成后所有信息素都会蒸发,但每个优化函数只有一个最优解获得信息素增加,经过多过蚁群周期后即可解获得最优解集.实验结果表明,该方法可为Web服务组合提供一种很好的优化方案,具有很高的准确率.     

A two-phase framework for quality-aware Web service selection

Service-oriented computing is gaining momentum as the next technological tool to leverage the huge investments in Web application development. The expected large number of Web services poses a set of new challenges for efficiently accessing these services. We propose an integrated service query framework that facilitates users in accessing their desired services. The framework incorporates a service query model and a two-phase optimization strategy. The query model defines service communities that are used to organize the large and heterogeneous service space. The service communities allow users to use declarative queries to retrieve their desired services without worrying about the underlying technical details. The two-phase optimization strategy automatically generates feasible service execution plans and selects the plan with the best user-desired quality. In particular, we present an evolutionary algorithm that is able to “co-evolve” multiple feasible execution plans simultaneously and allows them to compete with each other to generate the best plan. We conduct a set of experiments to assess the performance of the proposed algorithms.     

Efficient execution of composite Web services exchanging intensional data

Web service technologies provide a standard means of integrating heterogeneous applications distributed over the Internet. Successive compositions of new Web services using pre-existing ones usually create a hierarchical structure of invocations among a large number of Web services. For the efficient execution of these composite Web services, we propose an approach which exploits intensional XML data, i.e. an XML document that contains special elements representing the calls to Web services, in order to delegate the invocations of the external Web services to some relevant nodes. We formalize an invocation plan for composite Web services in which intensional data is used as their parameters and results, and define a cost-based optimization problem to obtain an efficient invocation plan for them. We provide an A∗ heuristic search algorithm to find an optimal invocation plan for a given set of Web services and also present a greedy method of generating an efficient solution in a short time. The experimental results show that the proposed greedy method can find a close-to-optimal solution efficiently and has good scalability for a complex call hierarchy of Web services.